Abstract : File characteristics: Software (37 files). Physical description: 1 computer diskette; 3 1/2 in.; high density; 1.44MB. System requirements: PC compatible; DOS; FORTRAN 77. Rotorcraft operations at heliports and airports are investigated to better understand and quantify the potential hazards associated with various types of rotorwash flow fields. Mathematical models for the various types are developed. These mathematical models are used in conjunction with hazard analysis models to develop an analysis methodology for evaluation of the potential for rotorwash-related mishaps in various operational scenarios. Correlation of all developed mathematical models with flight test, scale-model, and laboratory test data is provided wherever possible. Heliport design examples using the developed analysis methodology and the associated ROTWASH computer program are provided. This FORTRAN 77-based ROTWASH computer program can be used on PCs. There is one executable file for PC's with math coprocessors and a second executable file for PCs without coprocessors.